September 10 – Innocent, I tell ya!

Today’s factismal: DNA evidence can only be used to prove innocence, and never proves guilt.

We’ve all seen it on TV a zillion times by now: some investigator picks up a hair or piece of bubble gum and sends it off to the lab to be analyzed. Ten minutes later, the lab tech comes out and says “It’s a match! We’ve got him!” The only problem with that (as with most science shown on television shows) is that it is completely wrong.

In order to understand why, we need to step back in time some 29 years. A scientist by the name of Alec Jeffreys is trying to understand why some diseases tend to run in families. If a father has heart disease, then his sons are likely to have it as well. If a mother has diabetes, then her children probably will get it too. But why? Jeffreys was convinced that the answer to the question lies in the genetic code, so he made x-ray photographs of crystallized DNA (at the time, that was the only way to do it) that had been donated by his technician’s family. Though he thought that the images were a mess, he did notice that there were some surprising similarities between the images. He quickly realized that he had created a “fingerprint” of the DNA that could be used to tell if a person was related to another one.

His first case involved a boy from Ghana; the father insisted that he wasn’t related to the boy. Jeffreys ran his test and produced similar patterns, showing that the boy and the father were related. In his next case, Jeffreys was able to show that the main suspect in a series of rapes wasn’t related to whomever did the crime but that another suspect was; he had used DNA fingerprinting to show someone’s innocence.

Today the science of DNA fingerprinting has advanced considerably. Instead of looking at x-ray photographs of crystallized DNA, researchers sequence the DNA to identify the actual order of the units that make up the DNA. This test is a huge advance because it is faster, costs less, and uses less sample material than Jeffreys’ original method. But, like Jeffreys’ original method, it cannot show that the DNA came from a specific person; instead, all it can do is show that the DNA donor and the suspect are related – and a negative test proves innocence. Thus, a DNA test can never prove guilt, only innocence.

Of course, researchers are still trying to pin down the genetic components of disease. If you’d like to help them, then why not join the Personal Genome Project?

September 9 – Hole lotta trouble

Today’s factismal: The ozone hole stretched to cover a city for the first time fourteen years ago.

One of the great successes in pollution control was the 1992 international treaty banning the use of chlorofluorocarbons (CFCs) due to their effect on the ozone layer. Following the signing of the treaty, nations were required to change their refrigerators and hairsprays so that they didn’t use CFCs; the only exceptions were for national security. So with the pollution stopped, the problem was solved, right?

2009 Ozone Hole (Image courtesy NASA)

2009 Ozone Hole
(Image courtesy NASA)

Wrong. The problem with pollution is that it doesn’t stop doing harm just because you’ve stopped putting more trash into the atmosphere. You still have to deal with all of the junk that was put into the atmosphere before you stopped. Some environmentalists call this the “teenager’s room problem”: sure, your kid has gone to college and left his room empty – but you still have the ten years of empty soda cans, candy bar wrappers, and dirty laundry piled in the corners that need to be cleaned out before it can be turned into a sewing room. And that’s where we are with CFCs in the atmosphere. We’ve stopped adding them but we still have to wait for the ones in the air to break down and go away. And, until they do, we will have problems.

This year's ozone hole (Image courtesy MACC)

This year’s ozone hole
(Image courtesy MACC)

In 2000 we saw one example of the sort of problem we’ll have; the ozone hole grew to cover an area three times the size of the continental United States. It got so large that it covered all of Antarctica and part of South America, including the city of Punta Arenas. For two days, the residents were exposed to more UV radiation than normal. Though they haven’t reported much in the way of side effects that is because UV damage is a long-term problem (e.g., skin cancer, glaucoma) caused by a short-term exposure. Fortunately, that was the largest that the ozone hole has ever gotten; since then it has shrunken considerably.

Of course, a hole in the ozone layer isn’t the only problem we’ve got. If you’d like to help monitor air quality, then why not join NASA’s Citizens and Remote Sensing Observation Network Air Quality project?

September 8 – Broad Street Blues

Today’s factismal: A cholera epidemic was once stopped by removing a pump handle.

Cholera is one of those disgusting diseases that nobody likes. Princesses never die of it in fairy tales and heroes never conquer it – except in real life. And that’s a story far more interesting than any fairy tale!

The story starts, as all good stories must, long ago and far away in the hidden depths of India more than 2000 years ago. A bacterium decided that it wanted to give up its free-wheeling days and live in the human gut, just as millions of other bacteria do. Unfortunately for the people, the bacterium was Vibrio cholerae (“creator of cholera”). This unloveable little bug causes muscle cramps, restlessness, irritability, a rapid heart rate, vomiting and diarrhea. Without that last complication, it would be just another unpleasant form of food poisoning. But with it, the victim can lose so much water that they die. To make a bad thing worse, the diarrhea acts to spread the bug to yet more victims by contaminating the water supply.

Public (health) Enemy #1: Cholera (Image courtesy Dartmouth College)

Public (health) Enemy #1: Cholera
(Image courtesy Dartmouth College)

That last happens because it wasn’t until the turn of the last century that people started to realize that the best place for an outhouse was far away from the place they got their water; before then, the outhouse and the well were frequently side-by-side. As a result, any contamination from the outhouse could easily slip back into the well water and keep the cycle going. This was bad in the countryside. In a city, it was disaster.

Most cities were designed to get their water either from cisterns that were fed by aqueducts or from wells drilled under the city. And, until very recently, few cities had sewers capable of removing all of the “output” from their citizens; sewage often backed up and overflowed into the cisterns. And if some of that sewage happened to come from someone with cholera, an epidemic was born.

Our hero, John Snow (Image courtesy Wikipedia)

Our hero, John Snow
(Image courtesy Wikipedia)

That’s what happened in London in 1854. Large numbers of people were dying of cholera; more that 127 in the first three days of the epidemic and more than 600 before it was done. Those that could fled the city for safer climes. But the poorest people, who were also those most likely to get cholera, couldn’t flee. Luckily for them, a hero by the name of John Snow was able to track down the common factor in all of the cases: everyone was getting their water from the same pump. Though nobody at the time knew how cholera was transmitted (Snow suspected bacteria but couldn’t prove it), Snow had enough evidence to convince the town council to remove the pump handle at the center of the outbreak. With the handle gone, people stopped getting contaminated water and the outbreak was over and John Snow had helped invent the science of epidemiology.

If you’d like to help the epidemiologists of today, then why not work with them on chronic diseases at the Chronic Collaborative Care Network (C3N):

September 7 – Pigs in space

Today’s factismal: The first US satellite to carry biology experiments into space and back was launched 47 years ago today.

One of the more bizarre parts of space exploration has always been finding out how space travel would change critters. Would they grow as they normally did? Would they develop special powers and go on to be the world’s greatest superhero team? Or would they change in small but interesting ways? And, as is always the case in science, the only way to find out was to do the experiment. And experiment we did.

The first spiderweb spun in space (Image courtesy NASA)

The first spiderweb spun in space
(Image courtesy NASA)

We sent fruit flies, mice, rats, cats, dogs, guinea pigs, rhesus monkeys, frogs, and chimps into space, but all to test the life support systems to see if it was safe to send humans up. (Imagine if we tested pools that way…) After that question was answered, we started sending worms, spiders, fish, tortoises, yet more monkeys, fruit flies, brine shrimp, politicians, bacteria (but I repeat myself), silkworms, bees, ants, waterbears, and butterflies to see how their development changed once they’d been in space. You may have noticed a pattern to the critters that get sent; since the very beginning, we’ve preferred to send short-lived things because that allows us to have more generations of the critter exposed to space so that any changes will be more obvious.

A rhesus monkey grows to gigantic size after being exposed to space (not) (Image courtesy NASA)

A rhesus monkey grows to gigantic size after being exposed to space (not)
(Image courtesy NASA)

And we haven’t only sent animals; we’ve also sent plants. One of the longest running plants in space experiments also happens to be a citizen science experiment. Known as Tomatosphere, for the past eleven years it has involved sending tomato seeds up to the International Space Stations where they are exposed to outer space for nearly two years before being brought back down to Earth where they are sent out to school children to grow and measure. The results of this experiment will help us to understand how we can survive in space (and if tomatoes are just as tasty in zero gee). To take part, head over to:

(Those objecting to the experiment are advised to read this.)

September 6 – Tongue Tied

One of the best things about science is how it corrects mistakes. And one of the worst things about popular culture is how it perpetuates them. Today, Daniel, Peter, and Mary discover the truth behind a popular science myth when they get tongue tied!

It was a bright, sunny Saturday afternoon and life was just about perfect. Daniel had come to visit Mary and Peter that morning and they’d spent several hours experimenting with kites, trying to discover what sort of tail made a kite fly best. What they had discovered was that the person flying the kite was even more important than the tail. Peter’s kites always flew into trees or crashed into the ground. Mary could keep her kites flying but had a very hard time launching them. But Daniel was a natural kite-flyer and could make even the most unlikely of kites soar high above.

To make the day even better, when they’d gotten back to Mary’s back yard, they found that her father had set up a picnic for them, complete with hot dogs, potato salad, three kinds of pickles, and fresh watermelon. The three friends enthusiastically munched through the piles of food, only slowing down once they reached the slices of watermelon.

“Pass the salt, please,” Mary asked.

“I still don’t get it,” Daniel said as he salted his slice of watermelon and then passed her the condiment. “How can adding salt to watermelon make it taste so good?”

“Dunno,” Peter said. “It just does.”

“Is that any kind of attitude for a scientist to display?” Mary’s father chided gently. “A real scientist would try to figure it out.”

“OK, how do we do that?” Peter replied.

“In science, you always start with what you know. What do we know about taste?”

“Well, last year Mrs. Krabapple had us map our tongues with four tastes,” Mary said. “So we know that there are four different tastes and that they are in different parts of the tongue.”

“As a wise man once said, it isn’t what we know that causes us problem; it is what we think we know that really ain’t so,” her father said. “Your teacher was wrong on two counts. First, a taste isn’t found in just one part of your tongue. And second, there are more than four tastes.”

“Huh?” the three young scientists chorused.

“This is sort of like the myth of Brontosaurus which was really an Apatosaurus and the myth that we only use 10% of our brains when we actually use the whole thing. What happened is that a reporter misheard something and told everyone about it. What happened is that a psychologist by the name of Boring had translated a German paper that showed different parts of the tongue were more sensitive to different tastes. For some reason, this got reported by the popular press as though those tastes could only be sensed in those parts of the tongue. But you can easily prove that this isn’t true,” Mary’s father said.

“How?” Daniel asked.

“Spoken like a true scientist!” Mary’s father beamed. “First, stick out your tongue and dry it off with a napkin. That will make it certain that the taste doesn’t get spread by the saliva in your mouth. Now take a piece of water melon and touch it to the different parts of your tongue – on the front, on each side, in the middle, and in the back. See how you can taste it all over your tongue?”

The three experimenters followed his directions and quickly discovered that he was right. As they finished their experiment, he continued.

“Now watermelon has a lot of sugar in it, so you were mainly tasting ‘sweet’. We can repeat the experiment with the other tastes if you like, but what it will prove is that you have taste buds for every taste on every part of your tongue. There are actually taste buds on your cheeks and in your throat as well.”

“Wow!” Peter said. “Mrs. Krabapple never said anything about that!”

“She may not have known,” Mary’s father replied. “Sadly, many teachers don’t get the support they need in order to teach science properly.”

“But what about the number of tastes?” Mary demanded. “You said that there aren’t four tastes.”

“That’s right,” her father replied. “Depending on how you want to count them, there may be as few as five or as many as thirteen different distinct tastes. The five tastes that just about everyone agrees on are sweet, sour, bitter, salty, and umami.”

“Ohh-what-si?” Daniel asked.

“Umami,” Mary’s father repeated. “It is sometimes called ‘savoriness’ or ‘meatiness’ because it is sort of like the taste of a good steak. Those hot dogs you three scarfed down had a lot of umami.””That’s pretty neat, but what do the different tastes have to do with why we like watermelon better with salt on it?” Peter asked.”Ah, I think I’ll let you figure that out for yourselves. Stay here for a second!”With that, Mary’s father went back into their kitchen. Mystified, the three young scientists looked at each other. From the kitchen, they heard a variety of cabinets being opened and closed and the clink of plates. After a few minutes, Mary’s father came back out carrying five different plates. As he put the plates on the table in front of them, he explained what the experiment would be.”In each plate, we’ve got an example of a different taste. The first one has salt for saltiness. The second plate has baking cocoa for bitterness. The third plate has vinegar for sourness.  the fourth plate has low-sodium soy sauce for meatiness. And the last plate has sugar for sweetness. And here are a bunch of water crackers; they don’t really have much in the way of flavor,” he paused as Peter grabbed a cracker and tasted it.”Ugh!” Peter exclaimed. “It tastes like cardboard.””Right!” Mary’s father said. “Now here’s the experiment. First, you’ll dip a cracker into each of the different tastes and eat it. That will help you get familiar with the tastes. Then you’ll try dipping the cracker into two different tastes and then eat it. What do you think will happen?””Well, the two different tastes will just be two different tastes in our mouths,” Peter said. “Nothing will change.””I don’t know,” Daniel said. “Remember what happened when we added salt to the watermelon?””That’s right!” Mary exclaimed. “I’ll bet that the tastes change each other somehow.””Well, there’s only one way to be sure,” Mary’s father said. “Start tasting!”What do you think will happen? Try the experiment yourself!The three young scientists quickly grabbed crackers and dipped them into each of the plates. From their grimaces, it was clear that they didn’t much care for the tastes by themselves. But something changed when they started dipping the crackers into to tastes before eating them.”Hey!” Peter excitedly said. “Did you guys try this? Sweet plus bitter – it tastes almost like a candy bar!””Cool!” Daniel replied. “I like sour and salty – it tastes like a pickle!””And salty plus umami is wonderful!” Mary added. “This is so delicious!””Can you figure out why it is so good,” Mary’s father asked. “You’ve definitely got enough information to form a hypothesis now.””Well, one taste by itself isn’t very good,” Peter said. “And it only hits one set of taste buds.””But two different tastes together are good, ” Mary said.”And they hit two different sets of taste buds,” Daniel added. “So maybe the more different taste buds that get excited, the better the food tastes?””That’s right!” Mary’s father said. “That’s why the best recipes always have several different tastes in them. Cookies always have sweet and salty. Soda usually has sweet and  sour. Soup has umami and salty. And so forth. Companies spend billions of dollars trying to find the perfect combination of different flavors. For example, what do you think would happen if you used umami with your watermelon instead of salty? Or if you used bitter?””I don’t know,” Peter started.”But we sure want to find out!” Daniel and Mary chorused together. Smiling, the three scientists grabbed watermelon slices and began their most edible experiment of the day.

September 5 – Out of sight!

Today’s factismal: Voyager 1 was launched after Voyager 2.

You’d think that with all the smart people at NASA, they’d be able to get something as simple as naming a spacecraft right. And yet, they named the first spacecraft that took off for the outer Solar System “Voyager 2” (launched on August 20, 1977) and the second spacecraft “Voyager 1” (launched on September 5, 1977). But it turns out that there is a method to their madness; the probes were named for the order in which they would reach the planet Jupiter!

The Voyager 1 spacecraft (Image courtesy NASA)

The Voyager 1 spacecraft
(Image courtesy NASA)

You see, the Voyager program began as a “grand tour” of the Solar System. In the original plan, the probe would fly by all of the outer planets from Jupiter to Pluto. Unfortunately, just like a college sophomore who has to cut back his trip after his wallet is stolen, budget cuts at NASA meant paring back the probe design and the grand tour. Instead of two probes hitting all five planets, we had to settle for one probe that would visit Jupiter and Saturn (Voyager 1) and another probe that would visit Jupiter, Saturn, Uranus, and Neptune (Voyager 2). Poor Pluto would be left out in the cold until the launch of the New Horizons mission in 2006!

The path that the Voyager probes took (Image courtesy NASA)

The path that the Voyager probes took
(Image courtesy NASA)

Both missions went amazingly well, and we learned fantastic new things about all of the planets that they visited. We discovered rings around Jupiter and Neptune and Uranus, and the Solar System’s fastest cloud, and icy volcanoes on Triton. But even after the Voyager probes left the planets, they continued to do science. Right now, they are being used to map the edges of the Sun’s solar wind (what some astronomers refer to as the edge of the Solar System). Soon they will be surrounded by gas from interstellar space!

One of Voyager's more amazing discoveries - giant chevrons on Miranda (Image courtesy NASA)

One of Voyager’s more amazing discoveries – giant chevrons on Miranda
(Image courtesy NASA)

But the coolest part of the Voyager missions (and of most NASA missions) is that they make the data available for free to anyone who wants to use it. If you’d like to take a look at NASA data, then head over to My NASA Data and see what they have to offer!

September 4 – Turtles all the way down

Today’s factismal: Baby box turtles like to eat insects, slugs, and snails. Adult box turtles like to eat fruits and vegetables.

If you grew up in Oklahoma, Texas, or Louisiana, odds are that you had a box turtle for a pet as a child. And you probably wondered why your little turtle friend would never eat the lettuce that you put out for him. The answer is simple: just like young humans, young box turtles don’t eat their vegetables. Instead, they prefer to munch on insects, slugs, snails, and other turtle junk food. But, as they get older, the box turtle’s diet shifts and they start to eat more plants (probably because the plants can’t run away from them the way that insects do).

A box turtle sits on a rock, contemplating how he got into this predicament (My camera)

A box turtle sits on a rock, contemplating how he got into this predicament
(My camera)

That’s not the only way that box turtles are like people. Box turtles age at about the same rate that people do, too! Most box turtles grow very slowly after they hatch and only reach maturity (read: get ready to date) once they are about ten years old and six inches long. Female box turtles lay one or two clutches of eggs each year, with three to six eggs in each clutch. The adult box turtles then continue to chase plants and each other for the next twenty to forty years; some researchers even report seeing 100 year old box turtles!

But there’s something out there that may keep most box turtles from living that long: people. Many box turtles are taken to sell as pets or food, and others are killed by cars as the turtle crosses the road (Why? To get to the tossed salad!). As a result, the number of box turtles in the wild is shrinking. How far? We’re not sure. And that’s where you come in! If you spot a box turtle in Texas, then please report it to the Texas Nature Trackers: Box Turtle Survey Project. And then reward yourself with a nice, juicy worm! (Or an ice cream cone. Your choice.)